The invention relates to a battery box of the type having a plurality of interconnected cells with fluid flow channels arranged therebetween, for the purpose of maintaining a uniform desired temperature.
DE 41 16 253 C1 discloses a battery box of the generic type, in which the individual cells are combined to form cell groups and are supported, standing vertically, on the base side on ledges. A flow channel is formed by a separation between the sides of the cells in order to keep the individual cells at an appropriate temperature. The flow channels are connected to a distributor channel arranged in the base region of the battery box, and to a collecting channel, arranged in the region of the cover of the battery box. Each of the distributor channels is connected to the outside of the battery box via apertures arranged in the wall of the battery box.
A uniform flow through the flow channels must be achieved in order to assure that the individual cells are held at an appropriate temperature so that the battery box operates well. For this purpose, the free cross-section of the distributor channel reduces in the direction of the fluid flow, which keeps the cells at an appropriate temperature, and the cross-section of the collecting channel increases in the flow direction.
When battery boxes of this type are used for traction batteries in battery powered vehicles, it is necessary to optimize the use of existing physical space. In the case of a battery box of the generic type having vertical cells, it is, however, frequently impossible to increase the capacity or the voltage by arranging cells one above the other, for example in a second level, since this arrangement occupies at least double the physical height, and sufficient clearance is frequently not available (for example, for installation in a car boot or for underfloor installation). In addition, such a design creates problems with keeping the cells at an appropriate temperature, as well as with metrological detection of the temperature and of the voltage of the cells and cell groups.
The object of the invention is to provide an improved battery box of the generic type, in which utilization of the available physical space is made easier or improved, without adversely affecting the monitoring or control of cell temperatures.
The object is achieved according to the invention by a battery box in which a plurality of orientation independent cells (that is, cells which are operable in any orientation) are stacked horizontally relative to the installed position of the battery. This arrangement results in improved utilization of the height of the physical space which is available for the installation of the battery box, since the required physical height is only a multiple of the cell thickness and not of the cell height. Because the transverse flow channels are designed to provide for the fluid which keeps the cells at an appropriate temperature (especially of gases such as air etc.), the way in which the cells were previously kept at an appropriate temperature continues to be maintained.
In addition, this arrangement facilitates metrological monitoring of the battery box. That is, since the cells, which are combined to form cell groups, are fitted in a geometrically similar manner, a certain uniformity exists with respect to heat transfer and flow technology, and depending on the size of the cell groups, it is sufficient under some circumstances to use only one measurement signal for the temperature and/or the voltage as a measurement variable, for each cell group. Thus, as a result of the layered construction of the cell groups within the battery box, the individual stacks can be monitored, (for example, by detection of the fluid flowing through) with respect to temperature, flow rate, flow volume and voltage of the stack, in a simple manner in small units. More accurate localization is thus possible when a defect occurs. Furthermore, the incorporation of detectors for this purpose is simplified since their cables which pass to the exterior can be passed along the walls of the transverse flow channels, so that they form only a minor (and in general negligible) flow resistance for the cooling fluid.
The term cell groups is to be understood to mean a plurality of cells which are aligned in the vertical direction or stacked in the vertical direction over a base area. It is thus possible to form the base area (which also corresponds to the cover area) from a single cell, with a plurality of cells one behind the other, from a plurality of cells side by side, or from a combination of these two possibilities.